US3823290A

US3823290A - Electrical switchgear

Info

Publication number: US3823290A
Application number: US00340304A
Authority: US
Inventors: G Caton
Original assignee: Yorkshire Switchgear and Engineering Co Ltd
Current assignee: Yorkshire Switchgear and Engineering Co Ltd
Priority date: 1972-03-16
Filing date: 1973-03-12
Publication date: 1974-07-09
Anticipated expiration: 1991-07-09
Also published as: DK144958B; GB1418640A; CH579315A5; SE377220B; BE796881A; NL165876B; NL165876C; DE2312758B2; DE2312758A1; NO137066B; IT984419B; ZA731486B; FR2176084B1; NO137066C; JPS48102263A; NL7303621A; CA978249A; MY7700274A; AU5340873A; AU470682B2

Abstract

Electrical switchgear comprising a set of fixed contacts, a set of movable contacts mounted to close into engagement with the fixed contacts and to open out of engagement with the fixed contacts, a closing spring system having one or more springs, first movable restraining means restraining first ends of said springs, second movable restraining means restraining second ends of said springs, means connecting said second restraining means to move with the movable contacts; an opening spring system having one or more springs, third restraining means restraining first ends of said opening springs, and fourth restraining means restraining second ends of said opening springs; means connecting said third restraining means to said movable contacts; a first lever system for charging said closing spring system by moving said first restraining means independently of said movable contacts; a second lever system for charging said opening spring system by moving at least one of said third and fourth restraining means, such movement not being transmitted through said closing spring system; a first latch for releasably latching said closing spring system in its charged conditions, said first latch being operable when released to release said second restraining means and so allow said movable contacts to move to the closed position under the force in the charged closing spring system; and a second latch for releasably latching said opening spring system in its charged condition, said second latch being operable when released to release said third restraining means to allow said movable contacts to open under the force in the charged opening spring system.

Description

United StatesPatent n91 Caton ELECTRICAL SWITCHGEAR [75] Inventor: George Caton, Ilkley, England [73] Assignee: Yorkshire Switchgear and Engineering Co., Limited, Yorkshire, England [22] Filed: Mar. 12, 1973 [21] Appl. No.: 340,304

[30] Foreign Application Priority Data Mar. 16, 1972 Great Britain 12484/72 [52] US. Cl. 200/153 SC, 200/153 H [51] Int. Cl. I'I0lh 5/10 [58] Field of Search..... 200/153 SC, 153 H;'335/76; 185/37 R [56] References Cited UNITED STATES PATENTS 1,938,408 12/1933 Thumm 200/153 SC UX 3,551,627 12/1970 Bordak 200/153 SC FOREIGN PATENTS OR APPLICATIONS 1,093,871 l2/l960 Germany 200/153 SC Primary Examiner-Robert K. Schaefer Assistant Examiner-William J. Smith Attorney, Agent, or Firm-Stevens, Davis, Miller & Mosher [57] ABSTRACT Electrical switchgear comprising a set of fixed [11] 3,823,290 July 9, 1974 contacts, a set of movable contacts mounted to close into engagement with the fixed contacts and to open out of engagement with the fixed contacts, a closing spring system having one or more springs, first movable restraining means restraining first ends of said springs, second movable restraining means restraining second ends of said springs, means connecting said second restraining means to move with the movable contacts; an opening spring system having one or more springs, third restraining means restraining first ends of said opening springs, and fourth restraining means restraining second ends of said opening springs; means connecting said third restraining means to said movable contacts; a first lever system for charging said closing spring system by moving said first restraining means independently of said movable contacts; a second lever system for charging said opening spring system bytnoving at least one of said thirdand fourth restraining means, such movement not being transmitted through said closing spring system; a first latch for releasably latching said closing spring system in its charged conditions, said first latch being operable when released to release said second restraining means and so allow said movable contacts to move to the closed position under the force in the charged closing spring system; and a second latch for releasably latching said opening spring system in its charged condition, said second latch beingoperable when re leased to release said third restraining means to allow said movable contacts to open under the force in the charged opening spring system.

12 Claims, 5 Drawing Figures PATENTEBJUL 14 3,823,290

'

sum

2 or 5 PATENTED 9l974 3.823.290 SHEU 3 BF 5 PATENTEDJUL 91914 SHEET l 0F 5 -EIIII 11 3 PATENTEI] JUL 9:914

SHEET 5 BF 5 ELECTRICAL SWITCHGEAR This invention relates to switchgear for controlling high voltage electrical supplies.

The movable contacts of heavy duty switchgear are nowadays rarely closed or opened by manual operation alone. In conventional equipment manual operation of a handle is effective to charge two spring systems, an opening system for moving the movable contacts out of engagement with the fixed contacts, and a closing system for moving the movable contacts into engagement with the fixed contacts against the throw of forces created when closing against a short circuit current. In known arrangements the closing spring system works in opposition to the closing spring system, and the force charged in the closing system must be sufficient to charge the opening spring system and also to provide the force necessary to effect closing of the movable contact against the said forces.

According to the present invention electrical switchgear comprises a set of fixed contacts, a set of movable contacts mounted to close into engagement with the fixed contacts and to open out of engagement with the fixed contacts, a closing spring system having one or more springs restrained at'each end by first and second independently movable restraining means, the second of said means being connected to move with the movable contacts; an opening spring system having one or more springs restrained at each end by third and fourth restrianing means; a lever system for charging the closing spring system by moving the first restraining means independently of the movable contacts; a lever system for charging the opening spring system by moving at least one of the third and fourth restraining means, such movementnot being transmitted through the closing spring system; first and second latches for releasably latching the closing and opening spring systems in their charged conditions; the first latch being operable when released to release the second restraining means and so allow the movable contacts to move the closed position under the force in the charged closing spring system; and the second latch being operable when re leased to release the third restraining means which is connected to the movable contacts to open these under the force in the charged openingspring system.

This arrangement enables charging of the opening springsystem to be effected without the need to place an equal charge in the closing spring system, which thus.

need only be charged sufficiently to effect closure of the movable contacts.

Preferably the spring systems each comprise a number of parallel compression springs held between the respective restraining means, each spring having a rod running through its center, each rod being secured to one of the restrainingmeans and being movable relative to the other restraining means.

Alternatively systems of tension springs could be used.

Conveniently, the fourth restraining means is fixed, and the opening spring system is charged by moving the third restraining means towards the fourth restraining means. Alternatively, both third and fourth restraining means may be movable, charging being effected by relative movement of the restraining means towards each other. and particularly by moving the fourth restrainingmeans toward the third restraining means, which is held stationary.

Preferably a common lever system is provided for charging the two spring systems in order that charging may be effected by a single manual or powder driven operation. However, separate lever systems for the two spring systems could be used. Charging of the spring systems can be effected in any order, but it is preferred that the opening spring system be charged no later than the closing spring system. In a particularly preferred arrangement the two spring systems are charged simulta neously by movement of the first and third restraining means by a common lever system.

Preferably the movable contacts are pivotally movable about a pivot axis remote from the spring systems, although the invention may also be used in connection with linearly movable contacts.

The first latch is conveniently a toggle arrangement which is moved over center to release the movable contacts for movement to the closed position. On full opening of .the contacts the toggle moves back over center to hold the contacts in the open position and prevent them from bouncing back towards the fixed contacts.

In order that the invention may be better understood a specific embodiment of switchgear constructed in accordance therewith will now be described in more detail, with reference to the accompanying drawings, wherein: 7 FIG. 1 is a side elevation of the switchgear with the spring systems charged and the contacts open;

FIG. 2 shows the switchgear of FIG. 1 with the contacts closed after release of the closing springs;

FIG. 3 shows the switchgear of FIG. 1 with the contacts opened after release of the opening springs;

FIG. 4 is a plan view of the switchgear; and

FIG. 5 is a perspective view of the part of the switchgear removed from the housing.

As shown in the drawings the switchgear is contained in a housing 1 having a removable lid 2 secured by bolts such as 3 to the housing. Secured within the housing is an upper set of three horizontally aligned fixed contacts such as 4 and a lower set of three horizontally aligned fixed contacts such as 5. In the base of .the housing 1 there are provided a number of spaced support sockets 6. A shock absorber 7 comprising a closed cell expanded foam rubber or plastics material can also be lo: cated in the base of the housing. A rmeovable framework 8 having side members 8a and a transverse mem- I ber 8b fits within the housing 1 and is located at the bottom of the housing by means of a shaft 9 engaging.

the sockets 6, and by plateslO engaging lugs 11 towards the front comers of the housing; the plates and lugsbeing secured by nuts on studs 12 passing through holes 12a in the plates 10. The removable framework carries the movable contacts together with the control system for these, as will be described shortly. By mounting this mechanism on a removable framework, the whole of the mechanism can readily be lifted out of the housing 1 for maintenance or replacement purposes.

The shaft 9 is capable of pivoting on the sockets 6 and in the lower ends of side members 80, and secured to the shaft by plates 9a are a number of pairs of insulating arms 13 carrying movable contact assemblies 14 for engaging the fixed contacts 4 and 5. Each movable contact assembly 14 preferably comprises main contacts and auxiliary arcing contacts of known construction. The arms 13 canpivot withthe shaft 9 to move the movable contacts between the open position shown in FIG. 1 and a closed position shown in FIG. 2 wherein the movable contacts engage the fixed contacts. The arms 13 are connected at their upper ends by a cross member 15 to which are pivotally connected about an axis 16 two parallel arms '17. The arms 17 are each pivotally connected about an axis 18 to one end of lever amrs 19 which are secured to sleeves 20 journalled for rotation about a shaft 21 which in turn is rotatably mounted on the framework '8. The other ends of lever 19 are pivotally connected about an axis 22 to a bar 23 carrying a number of spaced restraining blocks 24, the bar 23 also being connected to the sleeve 20 by a further arm 24a. Each of the restraining blocks 24 has a rod 25 projecting therefron, the rods being slidably movable through holes in a restraining bar 26. Each of the rods 25 passes through the center of a compression spring 27. The compression springs 27 together form a closing spring system, the springs being restrained at one end by a first restraining means in the form of the restraining bar 26 and at the other end by second restraining means in the form of the restraining blocks 24.

The restraining bar 26 is pivotally secured about an axis 28 to two parallel arms 29 pivoted about axis 30 to carriers 31 secured to the framework 8. Also pivoted to the restraining bar 26 about axis 28 are two parallel arms 32 pivoted at their other ends about axis 33 to one arm of respective bell crank levers 34. The two bell crank levers 34 are each secured to sleeves 35 surrounding shaft 21 and secured to rotate therewith. The other arms of bell crank levers 34 have restraining blocks 36 pivoted thereto about an axis 37. Each restraining block 36 has a rod 38 secured thereto and projecting therefrom and the rods 38 are slidable through holes in a restraining bracket 38a secured to the framework 8. Surrounding each rod 38 is a compression spring 39 and the two springs 39 form an opening spring system restrained at one end by third restraining means comprising the restraining blocks 36 and at the other end by fourth restraining means comprising the restraining bracket 38a.

The mechanism is shown in FIG. 1 with both spring systems in their charged conditions and first and second latch arrangements are provided for holding these systems in this condition. The first latch arrangement is effective to hold the restraining blocks 24 in the position shown in FIG. 1. This latch system comprises-two identical toggle arrangements each comprising an arm 40 pivoted about axis 41 to lever 19 and an arm 42 pivoted at one end about axis 43 to arm 40 and its other end secured to a shaft 44 which is rotatably mounted on the framework 8. In the latched position shown the

pivotal axes

41 and 43 and the axis of the shaft 44 are in an over center condition which prevents lever 19 from rotating about the axis of shaft 21. These toggle systems thus hold restraining blocks 24 in the position shown.

The other latch system is effective to hold the bell crank levers 34 in the position shown in FIG. 1 and thus to hold the restraining bar 26 and restraining blocks 36 for the closing and opening spring systems respectively in the positions shown. This latch arrangement comprises a nose 45 projecting from one of the bell crank levers 34 and having a surface 46 engageable with a roller 47 rotatably mounted on a further bell crank lever 48 which is rotatably mounted about an axis 49 on the framework 8. The other arm of the lever has a striking pad 50 lying below a trip member 51 projecting upwardly through lid 2.

Operation of the switchgear will now be described. In order to close the movable contacts from the position shown in FIG. 1 shaft 44 is rotated in an anti-clockwise direction. This rotation may be effected by manual operation of a lever projecting through the housing 1 and having a part capable of engaging an arm 52 on the shaft 44 to cause the necessary anti-clockwise movement. This movement moves pivot axis 43 of the toggle systems from the over center position and thus allows levers 19 to pivot about axis 21. The charged force in the closing springs 27 thus drives the restraining blocks 24 to the left as shown in FIG. 1 so pivoting the levers 19 anti-clockwise and driving arms 17 to the right to pivot the movable contact arms 13 clockwise about the axis of shaft 9. The positionof the parts after this move ment are shown in FIG. 2. It will be seen that levers 17 and 19 form a straight toggle to provide a strut holding the movable contacts fully home.

Assume now that it is required to open the circuit by moving the movable contacts out of engagement with the fixed contacts. This is effected by depressing the trip member 51 so causing the lever 48 to pivot anticlockwise about its axis 49. Roller 47 thus moves out of engagement with surface 46 and the opening springs 39 are then free to drive the restraining blocks 36 to the left as seen in FIG. I. This has the effect ofpivoting bell crank levers 34 in a clockwise direction, these levers pushing against pins 41 carried by levers 19 so causing levers 19 to pivot clockwise about the axis 21 and thus move the movable contact arms back to the open position. The clockwise movement of levers 19 drives restraining blocks 24 of the closing spring system back to their original position, but the closing springs are not compressed as the clockwise movement of bell crank levers 34 also drive arms 32 to the right and this moves restraining bar 26 to the right. When the contacts are fully open the parts take up the positions shown in FIG. 3. When the opening spring system has driven the movable contacts to their open position it will be appreciated that the toggle mechanisms return to their over center positions. This has the effect of preventing a return movement of the lever 19 and so stops the movable contacts from bouncing back towards the fixed contacts.

The movable contacts are now in their open positions and both spring systems are discharged. In order to close the contacts again the spring systems must be recharged and this is effected by anti-clockwise rotation of shaft 21. This anti-clockwise rotation can be carried out electrically by a motor, solenoid or other power means, or by a manually operated lever system (not shown) outside the housing 1 driving a shaft 53 which moves a projection 54 engaging a lever 55 on the end of shaft 21 to drive the shaft 21 anti-clockwise. This movement pivots bell crank levers 34 anti-clockwise so pushing the restraining blocks 36 towards the restraining bracket 38a and compressing the opening spring system. During this movement the nose engages the roller 47 to pivot the trip lever 48 anti-clockwise and when the nose rises above the level of the roller 47 a clockwise spring bias on the trip lever 48 drives this into the position shown to hold the bell crank lever 34 as shown. At the same time as restraining blocks 36 are being moved to charge the opening springs, the other arm of hell crank levers 34 is pulling restraining bar 26 to the left to compress the closing springs against the stationary restraining blocks 24 held in their position by the toggle mechanisms.

Rotation of the

shafts

21 and 44 by pushing on to arms connected to these shafts when means secured to and projecting through the housing are operated, means that there is no fixed connection between these shafts and the housing 1. Thus removal of the framework 8 from the housing is unimpeded.

As is well known the contacts of certain types of high voltage switchgear are immersed in oil and in the present arrangement the housing 1 is filled with oil to the level 56. This oil is effective in suppressing arcing between the movable and fixed contacts and during such arcing gas is generated around the are which gas must be released from the housing 1. To effect this a passage 57 leads through the lid into an expansion chamber 58 fixed to the lid and the expansion chamber leads into a vent 59 to atmosphere. The fact that part of the movable contact opening and closing mechanism works below the level of the oil ensures that the whole of this mechanism is kept sufficiently lubricated due to splashing of oil onto parts of the mechanism normally above the oil level.

It will be noted that the switchgear described has no secondary electrical equipment included therein and this makes it eminently suitable for use in the switchgear arrangement described in our co-pending application Ser. No. 340,263 filed Mar. 12, 1973. In the arrangement described in that application a mechanical indication as to the position of the movable contacts is desirable and in the apparatus shown this indication is given by mean of two tappets 60 and 61 sliding in holes through the lid 2 and driving a rocker arm62 pivoted to a projection 63 from the lid. The lower ends of the two tappets engage an arm 64 pivoted on the shaft 12 and driven by lever 19. Accordingly when the movable contacts are open tappet 60 is raised and tappet 61 is lowered, but if the levers .19 pivot anti-clockwise to close the contacts this drives tappet 60 upwardly and tappet 61 moves to its downward position. Thus, the position of rocker arm 62 is an indication of the movable contact position, and may be used to drive a'visual indicator and also to control the operation of auxiliary switches mounted externally of the housing.

What I claim: I

1. Electrical switchgear comprising a set of fixed contacts; a set of movable contacts; means mounting said movable contacts for movement into a closed position in engagement with said fixed contacts and to an open position out of engagement with said fixed contacts; a closing spring system comprising at least one closing spring, first restraining means restraining said closing spring at a first end, and second restraining means restraining said spring at a second end, said first and second restraining means being independently movable; connecting means connecting said second restraining means to move with said movable contacts; an opening spring system comprising at least one opening spring, third restraining means restraining said opening spring at a first end, and .fourth restraining means restraining said opening spring at a second end; a lever system for charging said spring systems, said lever system including a bell crank lever having first and second arms, said first restraining means being pivotally con-.

nected to said first arm and said third restraining means being pivotally connected to said second arm, whereby movement of said lever systems drives said first and third restraining means in opposite directions simultaneously to charge the two spring systems in a single operation; and first and second latches for releasably latching said closing and opening spring systems in their charged conditions, said first latch being operable when released to release said second restraining means and allow said movable contacts to move to the closed position under the force in the charged closing spring system, and said second latch being operable when released to release said third restraining means which is connected to the movable contacts to move them to the opened position under the forcein the charged opening spring system.

2. Electrical switchgear according to claim 1 in which each said spring system comprises a number of parallel compression springs held between the respective ones of said restraining means, each spring having a rod running through its center, each said rod being secured to one of said respective restraining means and being movable relative to the other of said respective restraining means. i

3. Electrical switchgear according to claim 1 in which said first latch comprises a toggle lever system movable over center between a locking position and a release position.

4. Electrical switchgear according to claim 19 in which said toggle lever system comprises'a first toggle lever having first and second ends, a second toggle lever having first and second ends, means pivoting said first ends of said toggle levers together, meanspivoting said second end of said first toggle lever at a fixed location, and means pivoting said second end of said second toggle lever to a lever forming part of said connecting means between said second restraining means and said movable contacts.

5. Electrical switchgear according to claim 4 in which a common framework supports said movable contacts, spring systems, lever systems and latches, said framework is removably mounted in a housing to which said first contacts are secured, and said toggle lever system is movable over center to release said closing spring system by a release member extending tothe outsideof said housing.

6. Electrical switchgear according to claim 1 in which a nose is formed on said bell crank lever and said second latch is a roller engageable with said nose to prevent rotation of said bell crank lever in a direction allowing movement of said third restraining means to discharge said opening spring system.

7. Electrical switchgear according to claim 6 and including a further bell crank lever having first and second arms, said roller being mounted on said first arm of said further bell crank lever; a striking pad formed on said second arm of said further bell crank lever, and a trip member engageable with said striking pad to move said roller and release said second latch.

8. Electrical switchgear according to claim 7 in which a common framework supports said movable contact, spring systems, lever systems and latches, said framework is removably mounted in a housing to which said fixed contacts are secured, and said trip member is mounted for reciprocal movement in said housing and projects to the outside of said housing.

9. Electrical switchgear according to claim 1 in which said means mounting said movable contacts are pivot a second shaft rotatably supported on and projecting to the outside of said housing, and freely engaging elements on said first and second shafts, whereby said first shaft may be pivotally moved by appropriate pivotal movement of said second shaft.

12. Electrical switchgear according to claim 10 and including tappets extending to the outside of said housing, the positions of said tappets being controlled in accordance with the position of said movable contacts.

l l l

Claims

1. Electrical switchgear comprising a set of fixed contacts; a set of movable contacts; means mounting said movable contacts for movement into a closed position in engagement with said fixed contacts and to an open position out of engagement with said fixed contacts; a closing spring system comprising at least one closing spring, first restraining means restraining said closing spring at a first end, and second restraining means restraining said spring at a second end, said first and second restraining means being independently movable; connecting means connecting said second restraining means to move with said movable contacts; an opening spring system comprising at least one opening spring, third restraining means restraining said opening spring at a first end, and fourth restraining means restraining said opening spring at a second end; a lever system for charging said spring systems, said lever system including a bell crank lever having first and second arms, said first restraining means being pivotally connected to said first arm and said third restraining means being pivotally connected to said second arm, whereby movement of said lever systems drives said first and third restraining means in opposite directions simultaneously to charge the two spring systems in a single operation; and first and second latches for releasably latching said closing and opening spring systems in their charged conditions, said first latch being operable when released to release said second restraining means and allow said movable contacts to move to the closed poSition under the force in the charged closing spring system, and said second latch being operable when released to release said third restraining means which is connected to the movable contacts to move them to the opened position under the force in the charged opening spring system.

2. Electrical switchgear according to claim 1 in which each said spring system comprises a number of parallel compression springs held between the respective ones of said restraining means, each spring having a rod running through its center, each said rod being secured to one of said respective restraining means and being movable relative to the other of said respective restraining means.

4. Electrical switchgear according to claim 19 in which said toggle lever system comprises a first toggle lever having first and second ends, a second toggle lever having first and second ends, means pivoting said first ends of said toggle levers together, means pivoting said second end of said first toggle lever at a fixed location, and means pivoting said second end of said second toggle lever to a lever forming part of said connecting means between said second restraining means and said movable contacts.

5. Electrical switchgear according to claim 4 in which a common framework supports said movable contacts, spring systems, lever systems and latches, said framework is removably mounted in a housing to which said first contacts are secured, and said toggle lever system is movable over center to release said closing spring system by a release member extending to the outside of said housing.

9. Electrical switchgear according to claim 1 in which said means mounting said movable contacts are pivot mounting means mounting said movable contacts for movement about a pivot axis remote from said spring systems.

10. Electrical switchgear according to claim 9 in which a common framework supports said movable contacts, spring systems, lever systems and latches, and said framework is removably mounted in a housing to which said fixed contacts are secured.

11. Electrical switchgear according to claim 10 and including a first shaft pivotally journalled on said common framework and driving said common lever system, a second shaft rotatably supported on and projecting to the outside of said housing, and freely engaging elements on said first and second shafts, whereby said first shaft may be pivotally moved by appropriate pivotal movement of said second shaft.